Well, you could brush up on your math that you haven't looked at since you took your GCSE's - and any relevant science too. Practice talking and writing like a grown up (you're doing OK on this site so far), most older folks may not like text speak etc. If you haven't done much mechanical (or whatever type of engineering it is) maybe try and find some relevant books at the local library (if the govt hasn't closed it) to familiarize yourself with some of the terms. Look around the companies website etc. to get an idea what they do.
Try and research some of the practical jokes that the more experienced folks may play on you - for instance find out about 'sparks for the grinder', 'a long weight/wait' and similar classics.
Practice being "ever so 'umble" & respecting your elders - if you come across as a young know it all, or unwilling to pay your dues etc. or similar you'll have a hard time of it.
Over in the "How to Improve Myself to Get Ahead in My Work" forum you'll find various threads for new grads etc. in their first jobs - take a look at some of these.
Classics for once you get there would be:
'ask questions'
'write down the answers to the questions in a log book or similar'
'apply the answers to previous questions to new problems where possible
'rather than always asking direct questions try to propose what you think the answer is and ask them to confirm'
'remember you have 2 ears and one mouth, use them in that ration'
Good luck, we had an apprenticeship scheme at my former UK employer. Unfortunately about 1/2 the people in it didn't make the most of it, they didn't knuckle down to hard work, they only liked the fun part and they would call in sick or just not turn up etc. Now I'm not going to claim the company or apprentice scheme was perfect but some of them did take advantage of it and did well. A lot of the supervisors, managers, engineers etc. had gone through apprenticeships there and were doing OK.
Posting guidelines faq731-376 (probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484